CAP_UNFINISHED
if (l < 0 || l >= ms->level || ms->capture[l].len == CAP_UNFINISHED)
if (ms->capture[level].len == CAP_UNFINISHED) return level;
ms->capture[l].len = CAP_UNFINISHED; /* undo capture */
s = start_capture(ms, s, p + 1, CAP_UNFINISHED);
if (l == CAP_UNFINISHED) luaL_error(ms->L, "unfinished capture");